Mumtaz Qaumi, 31, escaped civil conflict in the Middle East only to become embroiled in a war of a different kind on Sydney's streets.

Qaumi, along with siblings Farhad and Jamil Qaumi, are awaiting sentence for their roles in the internal Brothers for Life gang conflict in 2013.

A conflict between the gang's Blacktown and Bankstown chapters sparked a series of shootings, including the death of Mahmoud Hamzy in Revesby Heights and serious injury of an innocent teenage girl.

Mumtaz and Farhad have also been convicted over organising the contract killing of debt collector Joe Antoun in Strathfield in 2013.

Letters and a psychiatric report tendered during a hearing in the NSW Supreme Court last week detailed Mumtaz's path to second-in-charge of the now-obliterated BFL gang.

Mumtaz, one of four children in a family that moved to Australia as refugees in the '90s, told a psychiatrist he had nothing to do with the BFL until receiving a call from his older brother, Farhad.

Farhad, leader of the Blacktown chapter, claimed people wanted him dead, prompting Mumtaz to "help protect his brother", the psychiatric report states.

Before that, Mumtaz jumped between jobs - and prison - working as a cleaner in Sydney department stores, a courier driver and finally a kebab shop owner.

In a letter to the court, his mother Gulmaki Qaumi, sought to explain her children's traumatic background.

"My children were raised in war-torn Afghanistan," she wrote.

"For over 10 years our family was subjected to horrifying conditions. There was often no medical aid, water or food available.

"We had only a single candle to light the basement in which we stayed. I still remember my children's hearts thumping in my ears."

The family escaped to India, she wrote, but without Mumtaz's father, who had been kidnapped.

Mumtaz told his psychiatrist his father turned up three years later, meeting them in India before they eventually moved to Australia.

However, his mother claimed the effects of war followed them.

"With a loud bang of a door, Farhad would put his hands over his ears, his face red, shaking and crying hysterically," she said.

"Mumtaz would wake up in a cold sweat, shivering as tears streamed down his face."

After being expelled from two high schools in his teens, Mumtaz later gave living a civilised adult life a crack, marrying his wife in 2007, buying a house in the western suburbs and becoming a father.

But by the time he turned 28, Mumtaz was organising shootings and instilling fear in gang members, all under his ruthless brother Farhad's direction.

Wife Wasillah Qaumi described her husband in 2013, when he suffered a back injury and stopped working, as a man with no friends who juggled depression.

"Since meeting Mumtaz, I never heard of him having a friend or going out with any friends as he was always at work or at home with myself or our children," she wrote in a letter to the court.

But in that same year she noticed a shift. Her husband started hanging out with "new friends" on the weekends. He drank socially and appeared happy, Mrs Qaumi wrote in a letter to the court.

It was also around this time he was spotted at The Star Casino, socialising with underworld figure Elias "Les" Elias and Farhad.

It would later emerge Elias paid Farhad and Mumtaz $190,000 to organise the murder of Antoun.

As tit-for-tat violence between the BFL chapters continued at the end of 2013, Mumtaz was on high alert.

"He would not let his family go out at night and he would always peek through the window when he heard a car drive past," his wife wrote in her letter.

"He told us not to answer the door if someone knocks at night. It seemed that he was in constant fear of his and his family's safety."

Now he is in Goulburn jail, where if he yells loud enough, he can talk to his brothers, Farhad and Jamil, who are held in nearby cells.

The Qaumis' sentencing hearing was adjourned to April 26.